Next for U of M geothermal effort: Pilot plant

Martin Saar (left), an earth sciences professor in the University of Minnesota’s College of Science and Engineering, and Jimmy Randolph, a research associate at the U of M and senior scientist at Heat Mining Co., shown here in 2011, developed the CPG process along with mechanical engineering professor Thomas Kuehn. (File photo: Bill Klotz)

A University of Minnesota startup expects construction to begin next year on a pilot plant that would produce electricity from geothermal and otherwise wasted energy while also boosting production from a Canadian oil field.

The plant would represent the first commercial application of a novel renewable energy technology called Carbon Dioxide Plume Geothermal, or CPG. The technology was developed at the U of M and is licensed to U of M startup Heat Mining Co. LLC, based in Rapid City, S.D.

The CPG plant would generate electricity from carbon dioxide that is injected underground, in a practice known as enhanced oil recovery (EOR), to increase the amount of crude oil extracted from a field that typically is nearing the end of its productivity.

The electricity generated using the CPG technology would be used to replace power provided by conventional sources, resulting in emission-free electricity at lower cost, extending the lifespan of economical oil extraction, according to its developers.

Pilot powers oil recovery

A portion of the carbon dioxide, warmed from the earth’s internal heat, would rise to the surface and expand to power a turbine in the pilot plant, generating electricity to drive the oil-recovery process. None of the carbon dioxide, a leading greenhouse gas associated with climate change and global warming, would be released to the atmosphere; rather, the carbon dioxide stays trapped in underground reservoirs.

“It would be the first of a kind but the opportunity to do that exists on an extremely broad basis there,” Ken Carpenter, Heat Mining Co. managing director, said. “There are literally thousands of these sites that could be converted to producing electricity using CPG technology. The opportunity to expand throughout the world is pretty big. Over the next decade there could be tens of thousands of megawatts of power produced using this technique just in the oil fields.”

Carpenter estimated that construction would begin by the middle of next year and that it would be operating at full capacity in the first quarter of 2016. He declined to say how much money Heat Mining Co., which is privately financed, had raised for the project or discuss additional details of the project

The company, which will not generate revenue until its first site is running, has just applied for, but not yet received, money from an organization in the Canadian province of Alberta that he said offers tens of millions of dollars a year for clean energy research and development work.

The pilot plant would produce five to 10 megawatts of electricity, said Jimmy Randolph, a research associate at the U and senior scientist at Heat Mining Co. Randolph developed the CPG process as a post-doctoral fellow with Martin Saar, an earth sciences professor in the university’s College of Science and Engineering, and mechanical engineering professor Thomas Kuehn.

One megawatt of electricity is usually considered enough to power 1,000 households, Randolph said.

50 to 100 CPG plants projected

Randolph estimated that second-generation CPG units would produce 10 megawatts of power each and cost $15 million apiece. “We’re projecting that within eight to 10 years, we could reasonably have 50 to 100 of those plants online, mostly limited by the rate at which we could build the power systems,” Randolph said.

The move into enhanced-oil recovery represents an expansion of the initial intent of the CPG energy production system, Saar said. The original focus was on using the CPG technology to capture carbon dioxide from fossil-fuel burning power plants and inject it into saline aquifers deep below the earth’s surface to sequester it, or keep it out of the atmosphere, in addition to using a portion of it to generate electricity.

The CPG system received a U.S. patent last November and has several international patents pending. The researchers have applied for follow-up patents to cover the use of CPG technology in enhanced oil recovery and to incorporate additional energy sources found at oil fields, such as waste heat from operations and natural gases such as methane that can surface in the recovery process. “There’s still a significant amount of flaring of these waste gases in the U.S. and around the world,” Randolph said. “A massive energy source is just being dumped now.”

Low-cost electricity

The follow-up patents also address incorporating energy sources that may be available at other industrial facilities, such as waste heat from ethanol or biofuel plants, Randolph said. Combining all of those energy sources enables the system to produce electricity at very low costs.

“We’re projecting we could produce power in the 2 to 4 cents per kilowatt hour range; that’s cost competitive with coal, natural gas and pretty much anything else,” Randolph said.

Saar, chief scientific officer of Heat Mining Co., said the company also envisions using CPG technology for grid-level storage of excess electricity from sources such as wind and solar farms. The CPG system can produce power intermittently, like wind and solar power sources, but in contrast to wind and solar, whenever power is actually needed, or as a base-load or continuous source of power.

Dr. Runar Nygaard, assistant professor of petroleum engineering at Missouri University of Science and Technology, said CPG electricity production is an interesting idea and a promising if underappreciated form of renewable energy.

“Geothermal is the missing focus on renewable energy,” Nygaard said. “There’s a lot of emphasis on solar and wind but we still overlook geothermal as a viable electricity source.”

Using carbon dioxide, instead of water to drive their CPG turbine is a key element that will help make the system more viable, Nygaard said.

“I think it will make CPG more attractive for enhanced oil recovery,” Nygaard said. “This is an intriguing technology, and especially linking additional heat from flare gas seems to be a good idea.”

NSF grant

The National Science Foundation last year awarded a highly competitive $1.9-million Sustainable Energy Pathways grant to Saar and members of an interdisciplinary team he put together, conducting scientific, engineering, economic and policy research into CPG technology.

The project previously received a $1.5 million grant from the U.S. Department of Energy that leveraged $400,000 in matching grants from university sources, Saar said. It earlier received a $600,000 grant from the university’s Initiative for Renewable Energy and the Environment, part of its Institute on the Environment.

“We’re getting more confirmation of the original theory,” Saar said. “When things deviate from the early simulations, they tend to be more on the positive side. We get more electricity out than we thought we could.”